The cat perception of bitter may differ from that of other mammals due to variations in their bitter receptor (Tas2r) genes. This study put together a functional characterization of domestic cat taste receptors.

Researchers functionally expressed two uncharacterized domestic sequences, Tas2r38 and Tas2r43, and deorphanized the receptors using a cellular functional assay. The cat sequence for Tas2r38 contains three major amino acid residues known to confer the taster phenotype (PAI), which is associated with sensitivity to the bitter compounds PROP and PTC. However, in contrast to human TAS2R38, cat Tas2r38 is activated by PTC but not by PROP. Furthermore, like its human counterpart, cat Tas2r43 is activated by aloin and denatonium, but differs from the human TAS2R43 by insensitivity to saccharin. The responses of both cat receptors to the bitter ligands were concentration-dependent and were inhibited by the human bitter blocker probenecid.

These data, according to researchers, demonstrate that the response profiles of the cat bitter receptors Tas2r38 and Tas2r43 are distinct from those of their orthologous human receptors. Results could be applied to the development of cat food products with more appealing flavor profiles.

Source: Michelle M. Sandau et al., 2015. A functional comparison of the domestic cat bitter receptors Tas2r38 and Tas2r43 with their human orthologs. MMC Neuro online, June 2015. doi: 10.1186/s12868-015-0170-6.